Super economical broadcast system and method   

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent Application Ser. No. 61/049,950 (filed on May 2, 2008), the contents of which is incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates, generally, to cellular communication systems. In particular, the present invention is related to a super economical broadcast system and method.

BACKGROUND OF THE INVENTION

Cellular radiotelephone system base transceiver stations (BTSs), at least for some United States (U.S.) and European Union (EU) applications, may be constrained to a maximum allowable effective isotropically radiated power (EIRP) of 1640 watts. EIRP, as a measure of system performance, is a function at least of transmitter power and antenna gain. As a consequence of restrictions on cellular BTS EIRP, U.S., EU, and other cellular system designers employ large numbers of BTSs in order to provide adequate quality of service to their customers. Further limitations on cells include the number of customers to be served within a cell, which can make cell size a function of population density.

One known antenna installation has an antenna gain of 17.5 dBi, a feeder line loss of 3 dB (1.25″ line, 200 ft mast) and a BTS noise factor of 3.5 dB, such that the Ga-NFsys=17.5−3.5−3.0=11 dBi (in uplink). Downlink transmitter power is typically 50 W. With feeder lines, duplex filter and jumper cables totaling −3.5 dB, the Pa input power to antenna is typically 16 W, such that the EIRP is 16 W+17.5 dB=1,000 W.

In many implementations, each BTS is disposed near the center of a cell, variously referred to in the art by terms such as macrocell, in view of the use of still smaller cells (microcells, nanocells, picocells, etc.) for specialized purposes such as in-building or in-aircraft services. Typical cells, such as those for city population density, have radii of less than 3 miles (5 kilometers). In addition to EIRP constraints, BTS antenna tower height is typically governed by various local or regional zoning restrictions. Consequently, cellular communication providers in many parts of the world implement very similar systems.

Restrictions on cellular BTS EIRP and antenna tower height vary within each countries. Not only is the global demand for mobile cellular communications growing at a fast pace, but there are literally billions of people, in technologically-developing countries such as India, China, etc., that currently do not have access to cellular services despite their willingness and ability to pay for good and inexpensive service. In some countries, government subsidies are currently facilitating buildout, but minimization of the cost and time for such subsidized buildout is nonetheless desirable. In these situations, the problem that has yet to be solved by conventional cellular network operators is how to decrease capital costs associated with cellular infrastructure deployment, while at the same time lowering operational expenses, particularly for regions with low income levels and/or low population densities. An innovative solution which significantly reduces the number of conventional BTS site-equivalents, while reducing operating expenses, is needed.

SUMMARY

Embodiments of the present invention provide a super economical broadcast system and method.

In one embodiment, a cellular communications system includes a plurality of base transceiver stations that define a plurality of respective cells, each base transceiver station includes a phased-array antenna having a plurality of sectors, each sector has a plurality of vertically-arranged antenna panels, and each antenna panel has a plurality of vertically-arranged radiators disposed in at least two staggered columns.

In another embodiment, a method for broadcasting signals using a phased-array antenna includes forming a horizontally and vertically shaped beam using a plurality of vertically-arranged antenna panels, in which each antenna panel has a plurality of vertically-arranged radiators disposed in at least two staggered columns, and transmitting a power distribution that has an essentially uniform field strength over a near zone, a middle zone and at least a portion of a far zone.

There have thus been outlined, rather broadly, certain embodiments of the invention, in order that the detailed description thereof herein may be better understood, and in order that the present contribution to the art may be better appreciated. There are, of course, additional embodiments of the invention that will be described below, and which will form the subject matter of the claims appended hereto.

In this respect, before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of embodiments in addition to those described and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein, as well as the abstract, are for the purpose of description and should not be regarded as limiting.

As such, those skilled in the art will appreciate that the conception upon which this disclosure is based may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a perspective view of a base transceiver station antenna, in accordance with an embodiment of the present invention.

FIG. 2 compares standard cell coverage with coverage provided by a base transceiver station antenna in accordance with an embodiment of the present invention.

FIGS. 3A and 3B depict horizontal and vertical radiation patterns for a phased-array antenna, in accordance with embodiments of the present invention.

FIGS. 4A and 4B illustrate various aspects of the “Robin Hood” principle, in accordance with embodiments of the present invention.

FIG. 5 illustrates antenna panel power and phase for phased-array antennas, in accordance with embodiments of the present invention.

FIG. 6 presents phased-array antenna signal strength as a function of distance, in accordance with embodiments of the present invention.

FIG. 7A depicts a perspective, semi-transparent view of a phased-array antenna panel, according to an embodiment of the present invention.

FIGS. 7B and 7C each depict a perspective view of a phased-array antenna panel, according to respective embodiments of the present invention.

FIGS. 8A, 8B, and 8C each depict a perspective view of an end portion of a phased-array antenna panel, according to respective embodiments of the present invention.

FIG. 9 depicts a perspective front view of a phased-array antenna panel, in accordance with an embodiment of the present invention.

FIG. 10 depicts a perspective rear view of a phased-array antenna panel, in accordance with an embodiment of the present invention.

FIG. 11 depicts a perspective view of an antenna panel stack, in accordance with an embodiment of the present invention.

DETAILED DESCRIPTION

Embodiments of the present invention provide a super economical broadcast system and method.

The inventive super economical broadcast system encompasses various antenna design and radio network planning concepts that solve the needs of cellular operators in GSM-960/1800/1900, CDMA-450/850 and UMTS-2170 standards with full support for all sub-standards and modulations in the 380 to 3,800 MHz frequency range. Advantageously, the inventive super economical broadcast system reduces specific capital expenditures and operational expenses, i.e., e.g., due to 10-30 times increase of a site\'s coverage area and application of optimized radio coverage planning methods, while exceeding standard technologies in terms of technical efficiency, applicability and profitability levels.

In accordance with various embodiments of the present invention, the number of required BTSs is decreased 10-20 times, maintaining or increasing quality of service, and allowing removing all redundant BTSs for use in new network construction or expansion of existing networks. This improved efficiency of resource management allows an operator to delay or even stop purchases of new equipment (BTS, transceivers), leading to economy of financial resources, higher profitability and increased business capitalization. Modernization of cells, in accordance with the teachings of the present invention, leads to better fault-tolerance of radio access networks due to implementation of modern and more reliable equipment. Maintenance expenses are also reduced, mean time between failures (MTBF) is significantly increased and total cost of ownership (TCO) of a cellular network is greatly reduced, keeping or even increasing profitability levels.

A preferred embodiment of the inventive super economical broadcast system includes, inter alia, installation of optimized sites with a maximal possible site capacity of 432 Erlang and a super long range, i.e., e.g., up to 40 km for indoor coverage. Anticipated costs per 1 km2 of network are more than ten times lower than costs of coverage created with cheaper and less qualitative BTSs and standard antennas. These optimized sites amplify signals both in their uplink and downlink channels, improving link budgets by 18-30 dB in comparison with standard antennas and masts, even for 10-20 times larger coverage areas. Amplification in downlink can reach as much as 80 W per carrier, allowing mobile terminals to reduce energy consumption and minimize RF interference.

These optimized sites are also characterized by maximal flexibility of capacity expansion, i.e., e.g., from an initial configuration of 7.5-15 Erlang to 432 Erlang (+2,880%) in mature networks. This ensures maximal adaptive capabilities for the network in contrasting demographic, economic and strategic conditions of modern telecommunication markets.

The inventive super economical broadcast system is similarly applicable to broadcasting networks, where powerful amplifiers and high-mounted antennas provide line-of-sight radio coverage on a territory within a radius of 40-50 km (5,000 to 8,000 km2).

The inventive super economical broadcast system advantageously allows an operator to quickly launch voice services with minimal capital expenditures on vast geographical areas, giving millions of people an opportunity to improve quality of their lives. This way, an operator receives economical and profitable technologies that may become key elements of business development strategies for many years to come. By adapting the teachings of the present invention, operators can tap into self-financing opportunities that may be supported by high, internal rates-of-return. An operator may well need only 15-25% of the total amount of capital expenditures to start a project self-financing process—the rest may be financed by large, generated gross profits.

The inventive super economical broadcast system may be most profitable in regions with relatively low spending levels on telecommunication services (ARPU US$1-4), with absent or old analogue telecommunication infrastructures. In such regions, a mobile cellular infrastructure with the lowest CAPEX levels (50-150 US$/km2) may provide the best economic and technical benefits. Flexibility in increasing a cell\'s capacity, operating expenses reduced by 50-95%, compatibility with all new standards (GPRS, EVDO, HSDPA, WiMAX, UMB, OFDM/MIMO) may jointly ensure that the lowest total cost of ownership and enable expansion into markets with low income and/or low population densities.

According to one aspect of the present invention, cell spacing, i.e., the distance between adjacent BTSs, is advantageously increased relative to conventional cellular systems while providing a consistent quality of service (QoS) within each cell. Preferred embodiments of the present invention increase the range of each BTS. Conventional macrocells typically range from about ¼ mile (400 meters) to a theoretical maximum of 22 miles (35 kilometers) in radius (the limit under the GSM standard); in practice, radii on the order of 3 to 6 ml (5-10 km) are employed except in high-density urban areas and very open rural areas. The present invention provides full functionality at the GSM limit of 22 ml, for typical embodiments of the invention, and extends well beyond this in some embodiments. Cell size remains limited by user capacity, which can itself be significantly increased over that of conventional macrocells in some embodiments of the present invention.

Commensurate with the increase in cell size, the BTS antenna tower height is increased, retaining required line-of-sight (for the customary 4/3 diameter earth model) propagation paths for the enlarged cell. Preferred embodiments of the present invention increase the height of the BTS antenna tower from about 200 feet (60 meters) anywhere up to about 1,500 ft (about 500 m). In order for the transmit power and receive sensitivity of a conventional cellular transceiver (user\'s hand-held mobile phone, data terminal, computer adapter, etc.) to remain largely unchanged, both the EIRP and receive sensitivity of the tower-top apparatus for the SEC system are increased at long distances relative to conventional cellular systems and reduced near the mast. These effects are achieved by the phased-array antenna and associated passive components, as well as active electronics included in the present invention.

Standard BTS equipment, such as transceivers, electric power supplies, data transmission systems, temperature control and monitoring systems, etc., may be advantageously used within the SEC system. Generally, from one to three or more cellular operators (service providers) may be supported simultaneously at each BTS, featuring, for example, 36 to 96 transceivers and 216 to 576 Erlang of capacity. Alternatively, more economical BTS transmitters (e.g., 0.1 W transmitter power) may be used by the cellular operators, further reducing cost and energy consumption. These economical BTSs have a smaller footprint and lower energy consumption than previous designs, due in part to performance of transmitted signal amplification and received signal processing at the top of the phased-array antenna tower rather than on the ground.

FIG. 1 presents a perspective view of a BTS antenna, in accordance with an embodiment of the present invention.

The base transceiver station 10 includes an antenna tower 12 and a phased-array antenna 14, with the latter disposed on an upper portion of the tower 12, shown here as the tower top. The antenna 14 in the embodiment shown is generally cylindrical in shape, which serves to reduce windload, and has a number of sectors 16, such as, for example, 6 sectors, 8 sectors, 12 sectors, 18 sectors, 24 sectors, 30 sectors, 36 sectors, etc., that collectively provide omnidirectional coverage for a cell associated with the BTS. Each sector 16 includes a number of antenna panels 18 in a vertical stack. Each elevation 20 includes a number of antenna panels 18 that can surround a support system to provide 360° coverage at a particular height, with each panel 18 potentially belonging to a different sector 16. Each antenna panel 18 includes a plurality of vertically-arrayed radiators, which are enclosed within radomes that coincide in extent with the panels 18 in the embodiment shown.

Feed lines, such as coaxial cable, fiber optic cable, etc., connect cellular operator equipment to the antenna feed system located behind the respective sectors 16. At the input to the feed system for each sector 16 are diplexers, power transmission amplifiers, low-noise receive amplifiers, etc., to amplify and shape the signals transmitted from, and received by, the phased-array antenna 14. In one embodiment, the feed system includes rigid power dividers to interconnect the antenna panels 18 within each sector 16, and to provide vertical lobe shaping and beam tilt to the panels 18 in that sector. In another embodiment, flexible coaxial cables may be used within the feed system.

FIG. 2 compares standard cell coverage with coverage provided by a BTS antenna according to an embodiment of the present invention. Table 1 compares antenna parameters and coverage for a conventional cellular site to two different embodiments of the present invention. The GSM 870-960 MHz band is used for this comparison.

TABLE 1 Standard 1st 2nd Site Embodiment Embodiment Antenna Parameters Sectors @ 3 @ 65° 6 @ 45° 9 @ 30° Beam Width Elevations 1 8 12 Panels 3 48 108 Antenna Aperture 2.5 m 20 m 30 m Installation Height 48 m 126 m 247 m Antenna Gain 17.5 dBi 28.0 dBi 31.0 dBi Uplink PL Efficiency +0.0 dB +26.6 dB +36.4 dB Signal Gain Factor 1 457 4365 Coverage Cell Radius 5 km 23 km 41 km Indoor Coverage Area 80 km2 1710 km2 5280 km2 Coverage Area Factor 1.0 21.4 66.1 Okumura-Hata exp. 4.0 4.0 4.0

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